This invention relates to a drive device which drives an auxiliary machine such as an oil pump or an air compressor used when a vehicle is running, the auxiliary machine being powered by a prime mover mounted in the vehicle.
Tokkai-Hei-10-75502 and Tokkai-Hei-10-51907 published by the Japanese Patent Office in 1998 disclose a hybrid vehicle provided with an engine and a motor which act as a prime mover for driving the vehicle. Since a hybrid vehicle stops the engine and runs only on the drive force of the motor in certain cases, an arrangement which drives an auxiliary machine only with the motive power of the engine can not be applied to a hybrid vehicle, the auxiliary machine such as an oil pump or an air compressor being used ordinarily when the vehicle is operating. Therefore, generally the motor drives the auxiliary machines described above in the hybrid vehicle. In this vehicle, an oil pump is used to generate an oil pressure which is supplied to a power steering device and an air compressor is used to generate an air pressure which is supplied to the braking system or the like. When there is an abnormality such as a malfunction in the motor system which drives the auxiliary machine, vehicle performance is compromised due to a lowering of oil pressure or air pressure.
The present invention has the object of maintaining the operation of an auxiliary machine when the vehicle is running, in the event of a malfunction in the motor system for driving the auxiliary machine.
In order to achieve the above object, the present invention provides a drive device for an auxiliary machine in a vehicle, the vehicle comprising a motor acting as a prime mover for the vehicle, a power transmission mechanism which transmits the output of the motor to the vehicle drive wheels and a motor for the auxiliary machine which powers the auxiliary machine in the vehicle. The drive device for the auxiliary machine in the vehicle comprises a power extraction mechanism which transmits a rotation of the power transmission mechanism to a drive shaft of the auxiliary machine, a solenoid clutch which enables or disables the transmission of the rotation to the auxiliary machine by the power extraction mechanism, a determination device for determining whether a control system of the motor for the auxiliary machine (including the motor for the auxiliary machine itself) is normal or abnormal, and a solenoid clutch control device which disengages the solenoid clutch when it is determined by the determination device that the control system of the motor for the auxiliary machine is operating normally and which engages the solenoid clutch when it is determined that the control system of the motor for the auxiliary machine is operating abnormally.
While the control system of the motor for the auxiliary machine is operating normally when the vehicle is running, the auxiliary machine is driven by the motor for the auxiliary machine because the solenoid clutch control device maintains the disengagement of the solenoid clutch. In contrast, when an abnormality occurs in the control system of the motor for the auxiliary machine when the vehicle is running (for example, a short circuit or a break in the cable supplying electrical power to the motor for the auxiliary machine, or an abnormality such as seizing of the rotation of the motor for the auxiliary machine), the abnormality is detected by the abnormality determination device. When the abnormality is detected in this manner, the rotation from the power transmission mechanism is transmitted through the power extraction mechanism to the drive shaft of the auxiliary machine such as an air compressor or an oil pump for power steering since the solenoid clutch control device engages the solenoid clutch.
In this manner, when there is an abnormality in the control system of the motor for the auxiliary machine, it is possible to maintain supply of oil pressure to the power steering device or of air pressure to the vehicle braking device because the auxiliary machine is operated by the drive force of the motor for driving the vehicle.
Another drive device is provided for an auxiliary machine in a vehicle, the vehicle comprising a motor acting as a prime mover for the vehicle, a power transmission mechanism which transmits the output of the motor to the vehicle drive wheels and a motor for the auxiliary machine which powers the auxiliary machine in the vehicle.
This drive device for the auxiliary machine in the vehicle comprises a spare auxiliary machine, a power extraction mechanism which transmits a rotation of the power transmission mechanism to the spare auxiliary machine, a solenoid clutch which enables or disenables the transmission of the rotation to the spare auxiliary machine by the power extraction mechanism, a determination device for determining whether a control system of the motor for the auxiliary machine (including the motor for the auxiliary machine itself) is normal or abnormal, and a solenoid clutch control device which disengages the solenoid clutch when it is determined by the determination device that the control system of the motor for the auxiliary machine is operating normally and which engages the solenoid clutch when it is determined that the control system of the motor for the auxiliary machine is operating abnormally.
While the control system of the motor for the auxiliary machine is operating normally when the vehicle is running, the auxiliary machine is driven by the motor for the auxiliary machine because the solenoid clutch control device maintains the disengagement of the solenoid clutch. In contrast, when the abnormality determination device determines that there is an abnormality in the control system of the motor for the auxiliary machine when the vehicle is running, the solenoid clutch control device engages the solenoid clutch and drives the spare auxiliary machine with the power transmission mechanism through the power extraction mechanism. In this manner, when there is an abnormality in the control system of the motor for the auxiliary machine, it is possible to continue supply of oil pressure to the power steering device or air pressure to the vehicle braking device by operating the spare auxiliary machine.
It is possible to provide a structure in which the solenoid clutch control device can forcibly engage the solenoid clutch even when there is not an abnormality in the control system of the motor for the auxiliary machine. When the control system of the motor for the auxiliary machine is operating normally, the auxiliary machine such as an oil pump or an air compressor is driven by the motor for the auxiliary machine. When the solenoid clutch is forcibly engaged, the spare oil pump or the spare air compressor is driven by the motor for driving the vehicle in addition to the auxiliary machine. Thus the output of the oil pump and the air pump is increased and it is possible to increase the working pressure of the braking device and the power steering.
In both the above inventions, the determination device for determining whether or not the control system of the motor for the auxiliary machine is normal or abnormal may comprise a rotation sensor detecting the rotation of the motor for the auxiliary machine, a rotation sensor detecting the rotation of the motor for driving the vehicle, and an abnormality determination device which determines that there is an abnormality in the control system of the motor for the auxiliary machine when the rotation speed of the motor for the auxiliary machine is less than or equal to a pre-set value during rotation of the motor for driving the vehicle. Since the motor for the auxiliary machine is normally driven when the vehicle is operating, it is possible to determine that there is an abnormality in the control system of the motor for the auxiliary machine, for example when the motor for the auxiliary machine is stopped while the motor for driving the vehicle is rotating.
Furthermore, in both the above inventions, it is possible to provide a warning device which outputs a warning when an abnormality in the motor for the auxiliary machine is detected. In this manner, it is possible to allow for timely repairs by notifying the driver with the warning that there is an abnormality in the control system of the motor for the auxiliary machine.